it looks like Galera replication will need to bundle the relevant session variables within the write-set when the write-set involves a query that has to be executed separately on each node, for example a DDL. In this case if the auto_increment* variables had been honoured then data inconsistency would not have been produced.

Moreover, the impact can be critical on a running cluster (losing 2 nodes on a 3 nodes cluster can have some consequences on traffic and response time if it is on a production cluster due to the fact that the cluster will run on one node only for a moment, from the time to restart others nodes then resyncing with SST ...)

IMO, this should normally not arrived in this case or in any case in a cluster environment as it is against the logic of having a cluster if finally all nodes but one go down !?

You can easily see it from the patch: just explicitly setting auto_increment_increrement and auto_increment_offset to 1 for the master thread before processing TOI action. Basically TOI actions don't need this autoincrement control at all due to strictly serial processing.